textproduct: Quad Cities

KEY MESSAGES

- Heat and humidity now looks to impact the area through the work week. The Heat Advisory has been expanded north and east slightly. If another extension in time to the headlines is needed, then we would be into the longevity aspect of the heat which may require an upgrade for parts of the area.

- The Storm Prediction Center has a Marginal, level 1 out of 5, Risk for severe storms in the Highway 20 corridor for this afternoon and tonight. Damaging winds are the primary risk with hail a secondary risk.

- There is a near daily risk of showers and storms for areas along and north of I-80. However, there will be plenty of dry hours.

UPDATE

Issued at 1257 PM CDT Tue Sep 1 2026

With higher sfc DPTs of mid to upper 70s pooling in the north closer to the boundary, have gone ahead and expanded the Heat Advisory acrs the rest of the DVN CWA. Some sites there in the new advisory area already well over a 100 degrees Heat Index.

SHORT TERM /THROUGH TONIGHT/

Issued at 224 AM CDT Tue Sep 1 2026

Some light showers or sprinkles will persist through sunrise in the weak lift occurring across the area. Over 95 percent of the area will remain dry.

The high moisture content of the atmosphere and light winds have created the ideal environment for fog development. Patchy ground fog has already developed with visibilities bouncing from several miles to near zero. Recent HRRR trends are now pointing toward more widespread fog development and thus a dense fog advisory has been issued for parts of the area. The fog will impact the morning commute. Visibility trends will need to be watched to see if the fog headlines need to be extended further to the south and east.

Hot and humid conditions will continue area wide today. NBM temperatures still look a tad warm but the delta has been slightly negative since yesterday.

Regardless, areas outside of the heat headlines will see peak afternoon heat indices of 95 to 100. Further south, peak heat indices will be around or just over 100 degrees.

With the heat dome building into the area, the rain chances have been confined to the Highway 20 corridor. Warm temperatures aloft may prevent any showers or thunderstorms from developing until late afternoon/evening. Any storms that do develop would be capable of producing damaging winds.

Tonight, the area looks to be mainly dry as the heat dome pushes the storm track into Minnesota and Wisconsin. Storms are expected to develop in South Dakota and grow upscale into a storm complex that moves east across southern Minnesota into Wisconsin.

Outflow boundaries from this complex may push into the northern areas and initiate nocturnal convection that may bring brief localized relief from the heat. However, any storms to do develop would be capable of producing damaging winds and potentially hail.

LONG TERM /WEDNESDAY THROUGH MONDAY/

Issued at 238 PM CDT Mon Aug 31 2026

The high heat and humidity continues through at least Thursday. Confidence in the hot conditions Wednesday through Thursday remain high, given the latest ECMWF EFI/Shift of Tails values for high temperatures are in excess of 0.8 to 0.9 (even some values over 0.95 in isolated spots), along with Shift of Tails values around 1. This suggests high confidence in anomalously warm high temperatures, although not extreme values based on the lower Shift of Tails. With the potential for these anomalously hot conditions to last this week, we've decided to extend the Heat Advisory another day (through Thursday). It's entirely possible for the advisory to be extended into Friday, given LREF ensemble exceedance probabilities of 100 degree heat indices exceeding 50% across our southern two tiers of counties. Additionally, overnight lows might not dip below 75 degrees through Wednesday night, so this would compound the heat stress - even at night. There is potential for some record warm low temperatures during this period. See the Climate section below for the current records.

In terms of thunderstorm activity for mid- to late-week, with the strongest part of the heat building for Wednesday, seems like the storm track will stay to our north. However, there is a signal for the edge of the heat dome to sink slightly southward Thursday and Friday, generating more active conditions during this time frame. NBM consensus model blends seem to keep the chances of precipitation north of the I-80 corridor (20-50% chances) for Thursday and Friday, so the extreme heat could still be in play, even into Friday. Uncertainty remains on the impact this activity will have on the heat potential for the northern forecast area, so stay tuned for updates throughout the week!

A look ahead to the upcoming weekend: the heat appears to diminish by the weekend, although there are some signals it will be more active, with additional chances of showers and storms. In terms of severe weather, this potential appears to be pretty low, given the lower probabilities from the various machine-learning severe prob resources.

AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 1257 PM CDT Tue Sep 1 2026

With the sfc boundary arching just to the north of the area, have gone with generally A VFR TAF fcst except for the DBQ site where being closer to the boundary may help the fog cause again there after midnight. Otherwise will bank on a persistent south to southwest sfc breeze of 4-6 KTs to keep VSBYs up at the rest of the sites, but may have to keep CID in mind for possible at least MVFR fog after 08z. DBQ and CID may also be suspect for isolated elevated showers or even a thunderstorm from this afternoon and into the overnight.

CLIMATE

Issued at 222 PM CDT Sun Aug 30 2026

Record Warm Low Temperatures:

September 1: KDBQ: 73/1937 KMLI: 75/1913

September 2: KDBQ: 74/2011 KMLI: 77/1913

September 3: KDBQ: 73/1939 KMLI: 76/1939

September 4: KDBQ: 71/1912 KMLI: 74/2018

DVN WATCHES/WARNINGS/ADVISORIES

IA...Heat Advisory until 7 PM CDT Thursday for IAZ040>042-051>054. Heat Advisory until 7 PM CDT Thursday for IAZ063>068-076>078- 087>089-098-099. IL...Heat Advisory until 7 PM CDT Thursday for ILZ001-002-017-018. Heat Advisory until 7 PM CDT Thursday for ILZ007-009-015-016- 024>026-034-035. MO...Heat Advisory until 7 PM CDT Thursday for MOZ009-010.